MOdel-Informed Precision Dosing of Ustekinumab and VEdolizumab in Inflammatory Bowel Disease

Inclusion Criteria: * Ulcerative colitis or Crohn's disease. Diagnosed, according to universally acknowledged criteria, a minimum of 3 months prior to inclusion * Age ≥ 18 * Stable treatment with VDZ or UST for at least 3 months prior to inclusion * Stable disease activity, mild activity is accepted, defined by fecal calprotectin ≤ 200, and a weighted PRO2 \< 14 for CD or a PRO2 ≤3 for UC * No change in medical therapy within 3 months prior to inclusion, as concomitant therapy with other immune suppressants is allowed (Azathioprine, 6-mercaptopurine, Methotrexate, 5-aminosalicylic acid) * The patient must be able to understand patient information material * The patient must be able to give informed written consent Exclusion Criteria: * Having a diagnose of indeterminate colitis * Having a stoma or pouch * Fistulizing disease being the primary reason for treatment with VDZ or UST * Expected eminent change of therapy * Expected need for surgical intervention within the coming 3 months * Contraindication against continuing treatment with VDZ or UST, including prior acute or delayed infusion reaction to VDZ or UST * Any active infection requiring parenteral treatment, known infection with tuberculosis, human immunodeficiency virus (HIV) or hepatitis virus. * Any condition which the responsible physician finds incompatible with participation in the study * Patients unable to participate in the collection of symptoms scores * Patients who are pregnant or nursing at time of inclu…